A pair of bicycles can become out of square in numerous ways. Ideally the bicycles stand in parallel vertical planes, but in practice the bicycle planes may toe in at front or rear, or either or both may be tipped in or out, or aspects of each of these problems may exist simultaneously. In use the bicycles are separately subject to loads, e.g. a speed bump or pot-hole, and this will apply torquing forces to the paired bicycles, or one bicycle may strike an object such as a curb, and the other not, their momentum producing a racking force which tries to carry one bike ahead farther than the other. And all these forces may be encountered in random combinations. The result is that previous attempts to have paired side-by-side, rather than tandem front to back, seat bicycles have not proved successful.
Tandem technology has been developed as an extension of basic bicycle frame technology and is well established, but for social riding tandem bicycles necessarily have the riders shouting into the wind in an effort to communicate. Mounting of two seats, two sets of pedals, and doubled handlebars on a single person frame has been attempted, but the result is unstable, dangerous, and at a minimum ungainly, See U.S. Pat. No. 4,178,008 to Barrett.
Various bracket combinations have been applied to side-by-side bicycles, See U.S. Pat. No. 1,522,039 to Swearinger, U.S. Pat. No. 3,350,115 to Ferrary, U.S. Pat. No. 3,870,338 to Holub, and U.S. Pat. No. 4,288,089 to Thiessen. But the vigor, randomness and variety of uneven loads has defied solution until the present invention wherein a stiff but not brittle chassis is used to control the positioning and force response of connector rods, enabling the bicycles to remain squarely aligned front-to-back, top-to-bottom and corner-to-corner in both a horizontal and a diagonal plane relative to the ground, despite the wear and tear of real world use.